Gen 2 easy jig is a good tool.

The Gen 2 easy jig is a good tool. I used a gen 2 7075 T6 80% lower that i bought from Brownells. The Router bit held up really good. I did have to go very slowly since i noticed that by going fast the router would vibrate a lot . I do recommend to continue drilling out the second pocket on the Gen 2 80% lower receivers since many uppers tend not to fit on the Gen 2 lower receivers because of that extra piece of aluminum in the way . I think that the Gen 2 80% lowers are made so that people won't be able to use an auto sear.

5/16 Hybrid End Mill Bit

I was unable to use the 5/16 hybrid end mill bit. This item is specifically for the Gen 2 Easy Jig. It is not compatible with the Gen 1 Easy Jig.
I cannot write about the quality of the bit, but the service was good for the return of the product. Just read all the documentation prior to ordering.

Easy Jig Gen 2

It uses the buffer tube of the lower with 2 pins to guarantee that it will be centered for milling. The Easy Jig Gen 2 is the only jig that requires one hole to be drilled. The steel of this jig is thicker than the Easy Jig Gen 2, and the side plates are also not touched by the end mill bit. The top plate is very smooth and the router slides easily, the only problem I see is that after milling a half a dozen lowers, the router plate surface is wearing and starting to get rough.